Browsing by Author "Liu, Kuan-Yu"

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A Dinitrosyliron Complex within the Homoleptic Fe(NO)(4) Anion: NO as Nitroxyl and Nitrosyl Ligands within a Single Structure
(2012-10-01)
Lin, Zong-Sian
;
Chiou, Tzung-Wen
;
Liu, Kuan-Yu
;
Hsieh, Chang-Chih
;
Yu, Jen-Shiang K.
Nitrosylation of the chelate thiolate-containing dinitrosyliron complex (DNIC) [(S(CH2)(3)S)Fe-(NO)(2)](-) triggers nitric oxide (NO) activation to generate the homoleptic nitrosyl {Fe(NO)(2)}(9) DNIC [Fe(NO)(4)](-) (1) made up of two nitroxyls (or two NO anions) attached to a delocalized {Fe(NO)(2)}(9) motif. The significantly longer N3-O3/N4-O4 [1.380(12) and 1.280(12) angstrom] and Fe1-N3/Fe1-N4 [2.008(11) and 2.045(10) angstrom] bond distances reflect that N3-O3 and N4-O4 of complex 1 may act as the nitroxyl-coordinated ligands. That is, the electronic structure of the DNIC 1 is best described as a {Fe(NO)(2)}(9) motif coordinated by two nitroxyl (NO-) ligands.
Dissociation kinetics of macrocyclic trivalent lanthanide complexes of 1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (DO2A)
(2011)
Lin, Chih-Cheng
;
Chen, Chia-Ling
;
Liu, Kuan-Yu
;
Chang, C. Allen
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生物科技學系
The [H(+)]-catalyzed dissociation rate constants of several trivalent lanthanide (Ln) complexes of 1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (LnDO2A(+), Ln = La, Pr, Eu, Er and Lu) have been determined in two pH ranges: 3.73-5.11 and 1.75-2.65 at four different temperatures (19-41.0. degrees C) in aqueous media at a constant ionic strength of 0.1 mol dm(-3) (LiClO(4)). For the study in the higher pH range, i.e. pH 3.73-5.11, copper(II) ion was used as the scavenger for the free ligand DO2A in acetate/acetic acid buffer medium. The rates of Ln(III) complex dissociation have been found to be independent of [Cu(2+)] and all the Ln(III) complexes studied show [H(+)]-dependence at low acid concentrations but become [H(+)]-independent at high acid concentrations. Influence of the acetate ion content in the buffer on the dissociation rate has also been investigated and all the complexes exhibit a first-order dependence on [Acetate]. The dissociation reactions follow the rate law: k(obs) = k(Ac)[Acetate] + K' k(lim)[H(+)]/(1 + K'[H(+)]) where k(AC) is the dissociation rate constant for the [Acetate]-dependent pathway, k(lim) is the limiting rate constant, and K' is the equilibrium constant for the reaction LnDO2A(+) + H(+) double left right arrow LnDO2AH(2+). In the lower pH range, i.e. pH 1.75-2.65, the dye indicator, cresol red, was used to monitor the dissociation rate, and all the Ln(III) complexes also show [H(+)]-dependence dissociation pathways but without the rate saturation observed at higher pH range. The dissociation reactions follow the simple rate law: k(obs) = k(H)[H(+)], where k(H) is the dissociation rate constant for the pathway involving monoprotonated species. The absence of an [H(+)]-independent pathway in both pH ranges indicates that LnDO2A(+) complexes are kinetically rather inert. The obtained k(AC) values follow the order: LaDO2A(+) > PrDO2A(+) > EuDO2A(+) > ErDO2A(+) > LuDO2A(+), whereas the k(lim) and k(H) values follow the order: LaDO2A(+) > PrDO2A(+) > ErDO2A(+) > EuDO2A(+) > LuDO2A(+), mostly consistent with their thermodynamic stability order, i.e. the more thermodynamically stable the more kinetically inert. In both pH ranges, activation parameters, Delta H*, Delta S* and Delta G*, for both acetate-dependent and proton-catalyzed dissociation pathways have been obtained for most of the La(III), Pr(III), Eu(III), Er(III) and Lu(III) complexes, from the temperature dependence measurements of the rate constants in the 19-41 degrees C range. An isokinetic (linear) relationship is found between Lambda H* and Lambda S* values, which supports a common reaction mechanism.
Effects of Interacting with a Crowd of Emotional Virtual Humans on Users' Affective and Non-Verbal Behaviors
(2020-01-01)
Volonte, Matias
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Hsu, Yu-Chun
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Liu, Kuan-Yu
;
Mazer, Joe P.
;
Wong, Sai-Keung
In this contribution we examined the effects on users during interaction with a virtual human crowd in an immersive virtual reality environment. We developed an agent-based crowd model with rich properties including eye gaze, facial expression, body motion, and verbal and non-verbal behaviors. The scenario was a virtual market in which the users needed to gather specific items. In a between subjects design, users interacted with a virtual human crowd that showed opposite valenced emotional expressions. There are four conditions in the between-subjects design. These includes different affective virtual crowds namely, Positive, Negative, Neutral, and a Mix condition. The Mix group is defined by a combination of Positive, Negative and Neutral emotional expressive characters. Depending on the specific condition, the virtual humans showed specific verbal and non-verbal behaviors. During the experiment we collected objective measures such as skin electrodermal activity, total time in the simulation, the number of interactions with the agents and performance measures. The subjective measures were the differential emotional survey (DES), and a user experience survey. We reported our findings with an in-depth analysis.
Electronic Structure of Open-Shell Tetrahedral {Fe(NO)(2)}(9) Dinitrosyliron Complexes
(2014-10-20)
Liu, Kuan-Yu
;
Yu, Jen-Shiang K.
;
生物科技學系
;
生物資訊及系統生物研究所
;
Department of Biological Science and Technology
High-level ab initio excited-state theory is employed to investigate the electronic structure of doublet {Fe(NO)(2)}(9) species in the ground state and compared with the results obtained by density functional theory. Both of the approaches consistently suggest that the linear NO ligands in dinitrosyliron complexes (DNICs) feature a radical character. Theoretical calculations also predict that the cyanide-supported DNIC anion of [(NC)(2)Fe(NO)(2)](-) features C-2 nu symmetry with a Fe-C-N bonding motif, and multireference theories suggest a minimal active space of CAS(9,9) to describe these {Fe(NO)(2)}(9) compounds, while larger CAS(13,13) calculations do not tend to significantly improve the geometries. Experimental vibration modes of NO ligands are also accurately assigned due to second-order n-electron valence state perturbation theory.
Interaction with proactive and reactive agents in box manipulation tasks in virtual environments
(2019-05-01)
Liu, Kuan-Yu
;
Volonte, Matias
;
Hsu, Yu-Chun
;
Babu, Sabarish V.
;
Wong, Sai-Keung
This paper studies the user collaboration experience with proactive and reactive agents in transporting boxes in virtual environments. Two main characters, the avatar and the agent, are controlled by a user and a controller, respectively. The user and the agent communicate with each other by voice. The agent can be proactive or reactive. The user follows the instruction issued by the proactive agent, whereas the user instructs the reactive agent to perform actions. The goal is to transport boxes to goal positions with orientation constraints. We conducted a user study to analyze the behaviors of participants in several aspects, including task completion time, path length, control experience, and co-presence experience. We report our findings and make suggestions for future development.
The formation stability, hydrolytic behavior, mass spectrometry, DFT study, and luminescence properties of trivalent lanthanide complexes of H(2)ODO2A
(2012)
Chang, C. Allen
;
Wang, I-Fan
;
Lee, Hwa-Yu
;
Meng, Ching-Ning
;
Liu, Kuan-Yu
The trivalent lanthanide complex formation constants (log K-f) of the macrocyclic ligand H(2)ODO2A (4,10-dicarboxymethyl-1-oxa-4,7,10-triazacyclododecane) have been determined by pH titration techniques to be in the range 10.84-12.62 which increase with increasing lanthanide atomic number, and are smaller than those of the corresponding H(2)DO2A (1,7-dicarboxylmethyl-1,4,7,10-tetraazacyclododecane) complexes. The equilibrium formation of the dinuclear hydrolysis species, e.g. Ln(2)(ODO2A)(2)(mu-OH)(+) and Ln(2)(ODO2A)(2)(mu-OH)(2), dominates over the mononuclear species, e.g. LnODO2A(OH) and LnODO2A(OH)(2)(-). Mass spectrometry confirmed the presence of [Eu(ODO2A)](+), [Eu(ODO2A)(OH)+H](+), [Eu-2(ODO2A)(2)(OH2)(2)+H](+), [Eu(ODO2A)(OH)(2)](-) and [Eu-2(ODO2A)(2)(OH2)(3)](-) species at pH > 7. Density function theory (DFT) calculated structures of the EuODO2A(H2O)(3)(+) and EuDO2A(H2O)(3)(+) complexes indicate that three inner-sphere coordinated water molecules are arranged in a meridional configuration, i.e. the 3 water molecules are on the same plane perpendicular to that of the basal N3O or N-4 atoms. However, luminescence lifetime studies reveal that the EuODO2A(+) and TbODO2A(+) complexes have 4.1 and 2.9 inner-sphere coordinated water molecules, respectively, indicating that other equilibrium species are also present for the EuODO2A(+) complex. The respective emission spectral intensities and lifetimes at 615 nm (lambda(ex) = 395 nm) and 544 nm (lambda(ex) = 369 nm) of the EuODO2A(+) and TbODO2A(+) complexes increase with increasing pH, consistent with the formation of mu-OH-bridged dinuclear species at higher pH. Additional DFT calculations show that each Y(III) ion is 8-coordinated in the three possible cis-[Y-2(ODO2A)(2)(mu-OH)(H2O)(2)](+), trans-[Y-2(ODO2A)(2)(mu-OH)(H2O)(2)](+) and [Y-2(ODO2A)(2)(mu-OH)(2)] dinuclear complex structures. The first and the second include 6-coordination by the ligand ODO2A(2-), one by the bridged mu-OH ion and one by a water molecule. The third includes 6-coordination by the ligand ODO2A(2-) and two by the bridged mu-OH ions. The two inner-sphere coordinated water molecules in the cis- and trans-[Y-2(ODO2A)(2)(mu-OH)(H2O)(2)](+) dinuclear complexes are in a staggered conformation with torsional angles of 82.21 degrees and 148.54 degrees, respectively.